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Posted by Bruce L. Bergman on March 22, 2008, 1:24 am
Please log in for more thread options
On Fri, 21 Mar 2008 23:24:48 -0400, "Shawn" <shawn_75ATcomcastDOTnet>
wrote:
>> The GTE Splicer trucks and vans all carried a large (200CF range)
>> Nitrogen cylinder horizontally for air tools and cable pressurization,
>> you would chain the bottle to the pole if you needed to leave it in
>> the field. (And I suppose they still do since the work remains the
>> same, though the racks may have been upgraded.)
>>
>snip>
>> --<< Bruce >>--
>
>Bruce,
>
>I often see bottles strapped to poles after some work has been done on a
>splice (I assume). What is the nitrogen used for after they are complete?
>Sometimes I have seen the bottles left for over a week.
>
>Shawn
Depends - sometimes you are doing work in the middle of a cable run,
and they suspect a leak in an underground cable at the far end of the
run - and if there's a manhole at the other end that is full of water
where the leak might be, when the air pressure goes away the cable
could end up full of water...
It's bad enough on the newer plastic insulated cable because it can
be dried out, but with older paper insulated cables you get any free
water inside and any cable that got damp is trash - and that little
leak quickly becomes a major 1200 to 4200-customer outage disaster...
They'll put air on at the far end, past where you opened the cable
to work. That way the leak you cause with the splice case open
doesn't depressurize all the cable past you - now it's feeding from
the bottle back toward you and leaking from both ends at the case
you've opened. Meaning it still has the full 10 PSI on the cable
toward the CO and the far end, except for about 1 case either way and
1/8 mile that will see a reduction.
If the bottle is only left there a few days, it's because they're
working on that run. If it's there semi-permanently, the pressure man
(person...) in your area is either overworked or lazy, and there's a
persistent leak he hasn't found and fixed.
They feed air on all cables from the switchroom, with a compressor
and air dryer, and they have pressure transducers at the far ends to
monitor the pressure - you have to call in and tell the office you are
working on that cable, or they'll get an alarm and send the pressure
man out to find the trouble.
If you are in a rural area with really long cables, they run more
bottles just because of pressure drop and latency several miles form
the switchroom. If there is a need for one, they will stick a
pedestal mounted electric compressor and air dryer in the field, and
feed several cables from the far end.
Oh, and the power company also has some air-core cables deployed,
but they usually do theirs differently so you can tell. The L.A. DWP
hangs their Nitrogen bottles off the pole in a chain sling about 10
feet up, keeps the kiddies from playing with them.
Their bottles are often there semi-permanently, for example to
pressurize a little chunk of air-core underground cable where the 10KV
to 35KV feeder line changes from aerial to go under the freeway, then
back to aerial on the other side. If that cable (or cables plural)
isn't being fed air from a distribution station compressor, they need
a bottle on it. Wet power cables go BOOOOM!!
--<< Bruce >>--
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Posted by Pete C. on March 22, 2008, 8:26 am
Please log in for more thread options
"Bruce L. Bergman" wrote:
>
> On Fri, 21 Mar 2008 23:24:48 -0400, "Shawn" <shawn_75ATcomcastDOTnet>
> wrote:
>
> >> The GTE Splicer trucks and vans all carried a large (200CF range)
> >> Nitrogen cylinder horizontally for air tools and cable pressurization,
> >> you would chain the bottle to the pole if you needed to leave it in
> >> the field. (And I suppose they still do since the work remains the
> >> same, though the racks may have been upgraded.)
> >>
> >snip>
> >> --<< Bruce >>--
> >
> >Bruce,
> >
> >I often see bottles strapped to poles after some work has been done on a
> >splice (I assume). What is the nitrogen used for after they are complete?
> >Sometimes I have seen the bottles left for over a week.
> >
> >Shawn
>
> Depends - sometimes you are doing work in the middle of a cable run,
> and they suspect a leak in an underground cable at the far end of the
> run - and if there's a manhole at the other end that is full of water
> where the leak might be, when the air pressure goes away the cable
> could end up full of water...
>
> It's bad enough on the newer plastic insulated cable because it can
> be dried out, but with older paper insulated cables you get any free
> water inside and any cable that got damp is trash - and that little
> leak quickly becomes a major 1200 to 4200-customer outage disaster...
>
> They'll put air on at the far end, past where you opened the cable
> to work. That way the leak you cause with the splice case open
> doesn't depressurize all the cable past you - now it's feeding from
> the bottle back toward you and leaking from both ends at the case
> you've opened. Meaning it still has the full 10 PSI on the cable
> toward the CO and the far end, except for about 1 case either way and
> 1/8 mile that will see a reduction.
>
> If the bottle is only left there a few days, it's because they're
> working on that run. If it's there semi-permanently, the pressure man
> (person...) in your area is either overworked or lazy, and there's a
> persistent leak he hasn't found and fixed.
>
> They feed air on all cables from the switchroom, with a compressor
> and air dryer, and they have pressure transducers at the far ends to
> monitor the pressure - you have to call in and tell the office you are
> working on that cable, or they'll get an alarm and send the pressure
> man out to find the trouble.
>
> If you are in a rural area with really long cables, they run more
> bottles just because of pressure drop and latency several miles form
> the switchroom. If there is a need for one, they will stick a
> pedestal mounted electric compressor and air dryer in the field, and
> feed several cables from the far end.
>
> Oh, and the power company also has some air-core cables deployed,
> but they usually do theirs differently so you can tell. The L.A. DWP
> hangs their Nitrogen bottles off the pole in a chain sling about 10
> feet up, keeps the kiddies from playing with them.
>
> Their bottles are often there semi-permanently, for example to
> pressurize a little chunk of air-core underground cable where the 10KV
> to 35KV feeder line changes from aerial to go under the freeway, then
> back to aerial on the other side. If that cable (or cables plural)
> isn't being fed air from a distribution station compressor, they need
> a bottle on it. Wet power cables go BOOOOM!!
>
> --<< Bruce >>--
I've noticed a few places that seem to have big enough issues to take
three or four normal high pressure nitrogen cylinders and one or two
where they went up to the big cryo cylinders for more capacity.
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Posted by Shawn on March 24, 2008, 7:55 am
Please log in for more thread options
> On Fri, 21 Mar 2008 23:24:48 -0400, "Shawn" <shawn_75ATcomcastDOTnet>
> wrote:
>
>>> The GTE Splicer trucks and vans all carried a large (200CF range)
>>> Nitrogen cylinder horizontally for air tools and cable pressurization,
>>> you would chain the bottle to the pole if you needed to leave it in
>>> the field. (And I suppose they still do since the work remains the
>>> same, though the racks may have been upgraded.)
>>>
>>snip>
>>> --<< Bruce >>--
>>
>>Bruce,
>>
>>I often see bottles strapped to poles after some work has been done on a
>>splice (I assume). What is the nitrogen used for after they are complete?
>>Sometimes I have seen the bottles left for over a week.
>>
>>Shawn
>
> Depends - sometimes you are doing work in the middle of a cable run,
> and they suspect a leak in an underground cable at the far end of the
> run - and if there's a manhole at the other end that is full of water
> where the leak might be, when the air pressure goes away the cable
> could end up full of water...
>
> It's bad enough on the newer plastic insulated cable because it can
> be dried out, but with older paper insulated cables you get any free
> water inside and any cable that got damp is trash - and that little
> leak quickly becomes a major 1200 to 4200-customer outage disaster...
>
> They'll put air on at the far end, past where you opened the cable
> to work. That way the leak you cause with the splice case open
> doesn't depressurize all the cable past you - now it's feeding from
> the bottle back toward you and leaking from both ends at the case
> you've opened. Meaning it still has the full 10 PSI on the cable
> toward the CO and the far end, except for about 1 case either way and
> 1/8 mile that will see a reduction.
>
> If the bottle is only left there a few days, it's because they're
> working on that run. If it's there semi-permanently, the pressure man
> (person...) in your area is either overworked or lazy, and there's a
> persistent leak he hasn't found and fixed.
>
> They feed air on all cables from the switchroom, with a compressor
> and air dryer, and they have pressure transducers at the far ends to
> monitor the pressure - you have to call in and tell the office you are
> working on that cable, or they'll get an alarm and send the pressure
> man out to find the trouble.
>
> If you are in a rural area with really long cables, they run more
> bottles just because of pressure drop and latency several miles form
> the switchroom. If there is a need for one, they will stick a
> pedestal mounted electric compressor and air dryer in the field, and
> feed several cables from the far end.
>
> Oh, and the power company also has some air-core cables deployed,
> but they usually do theirs differently so you can tell. The L.A. DWP
> hangs their Nitrogen bottles off the pole in a chain sling about 10
> feet up, keeps the kiddies from playing with them.
>
> Their bottles are often there semi-permanently, for example to
> pressurize a little chunk of air-core underground cable where the 10KV
> to 35KV feeder line changes from aerial to go under the freeway, then
> back to aerial on the other side. If that cable (or cables plural)
> isn't being fed air from a distribution station compressor, they need
> a bottle on it. Wet power cables go BOOOOM!!
>
> --<< Bruce >>--
>
Wow, thanks Bruce. I had no idea there was so much going on with those
cables.
Shawn
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Posted by on March 22, 2008, 9:49 am
Please log in for more thread options On Mar 21, 9:24=A0pm, "Shawn" <shawn_75ATcomcastDOTnet> wrote:
s:u0k7u3192h4qg500hr70ncvf7aq0c1rih0@4ax.com...
>
>
>
>
>
> > =A0The GTE Splicer trucks and vans all carried a large (200CF range)
> > Nitrogen cylinder horizontally for air tools and cable pressurization,
> > you would chain the bottle to the pole if you needed to leave it in
> > the field. =A0(And I suppose they still do since the work remains the
> > same, though the racks may have been upgraded.)
>
> snip>
> > =A0 =A0 =A0--<< Bruce >>--
>
> Bruce,
>
> I often see bottles strapped to poles after some work has been done on a
> splice (I assume). =A0What is the nitrogen used for after they are complet=
e?
> Sometimes I have seen the bottles left for over a week.
>
> Shawn
Man, it's been so long since I've seen one of those setups! They went
through our area when I was in grade school and replaced all the old
lead-sheathed pulp cables with silicone grease-filled ones. Buried
all the overhead long-distance cables, too, I briefly worked for a
contractor doing that. They used to blow dry nitrogen through those
old cables to dry them out, the wire separators were strands of paper
pulp. Wet cables were noisy. If there were a LOT of leaks, the
bottles would stay hooked up more or less semi-permanently. I guess
they considered it cheaper than replacing that segment of cable.
Probably these days they won't replace ANY cable if they don't have
to, for one thing the phone companies don't have the tech force
anymore.
Stan
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Posted by Gerald Miller on March 22, 2008, 7:21 pm
Please log in for more thread options On Sat, 22 Mar 2008 09:19:21 -0700, Bruce L. Bergman
>
> Not worth the hassle to go into a case to fix 2 or 3 shorts out of
>3600 pairs, you might find and fix one but create 2 or 3 new ones from
>moving things around...
>
> --<< Bruce >>--
5+ years ago, Bell replaced the local back yard feeder cable on the
other side of my street because the old one had too many repairs. When
they hooked it in to the transverse feeder which is in an easement
along my side lot line they found four bad pairs and had a look in my
yard where they found my topsoil pile at about the right distance back
along the line. The supervisor apparently didn't believe me that this
was only storage and not fresh digging and arranged all the locates
etc. to investigate. At my suggestion, he brought in a backhoe to my
yard, rather than a banjo crew since I had no problem with access. I
also provided the crew with washroom facilities, drinking water and
picnic table.
After they cut off my phone and Internet access, TV cable to the
subdivision, their own 400 pair cable, and were getting close to the
main HV feeders, he did some more research an discovered that this
fault was in an old splice and had been recorded some twenty years
previously, and even though I suggested that they might just as well
fix it while the splicing crew was already working on site, he
declined. I guess it makes a big difference when there is no chance of
recovering costs from the landowner.
Gerry :-)}
London, Canada
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>> Nitrogen cylinder horizontally for air tools and cable pressurization,
>> you would chain the bottle to the pole if you needed to leave it in
>> the field. (And I suppose they still do since the work remains the
>> same, though the racks may have been upgraded.)
>>